1. Field
The following description relates to a battery module with electrically connected rechargeable batteries.
2. Description of Related Art
Rechargeable batteries can be charged and discharged. Small capacity rechargeable batteries are used for small portable electronic devices such as mobile phones, laptop computers, and camcorders, while large capacity batteries are used as power sources for driving motors of hybrid vehicles, etc.
High power battery modules using a high energy density non-aqueous electrolyte have been developed, and the high power battery modules are formed as large-capacity battery modules by connecting a plurality of rechargeable batteries in series to be used for driving the motors of electric vehicles, etc.
Further, one large capacity rechargeable battery is generally composed of a plurality of rechargeable batteries connected in series, in which the rechargeable battery may be formed in a cylindrical shape or a prismatic shape.
Prismatic rechargeable batteries include a case having an electrode assembly in which a positive electrode and a negative electrode are disposed with a separator therebetween, and a space where the electrode assembly is disposed, a cap plate sealing the case and having a terminal hole where an electrode terminal is inserted, and an electrode terminal that is electrically connected with the electrode assembly and protrudes outside the case through the terminal hole.
The electrode terminal is fixed to the cap plate by a nut, but the nut can be loosened by continuous external vibration or shock. This causes contact resistance inside the rechargeable batteries, such that the output and cycle-life of the rechargeable batteries are reduced.
In particular, when a positive electrode terminal is made of aluminum and a negative electrode terminal is made of copper, since a connecting member and at least one of the positive electrode terminal or the negative electrode terminal are made of different materials, corrosion may occur or contact resistance may be continuously increased by contact between the different metals.
A method of connecting a connecting member to the positive electrode and the negative electrode using resistance welding has been proposed.
However, when the connecting member is made of a different material from that of at least one of the positive electrode terminal or the negative electrode terminal, it is difficult to bond the connecting member and the terminals with different materials using resistance welding or ultrasonic welding because of the different melting points.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.